1. Field of the Invention
The present invention relates to an optical member that has an optical film with an end face covered by a water-repellent material and has improved water resistance. Especially this invention relates to an optical member comprising a polarizing plate including a polarizer whose end face of is covered by a water-repellent material. Moreover, this invention relates to a method for producing the optical member. Moreover, this invention relates to an adhesive optical member, which an adhesive layer is prepared on the optical member and furthermore this invention relates to an image viewing displays such as a liquid crystal display, an organic electroluminescence display, and a PDP, using the optical member or the adhesive optical member.
2. Description of the Related Art
In liquid crystal displays, due to the image picture displaying system thereof, disposition of a polarizer on both sides of a glass substrate provided on a top surface of a liquid crystal panel is inevitably required. Therefore, in general, a polarizer is used with protective films laminated thereto as a polarizing plate. Moreover, in order to improve display quality of displays, optical members laminating various optical films on polarizing plates are increasingly used. For example, a retardation film for coloring prevention, a viewing angle compensation film for improving viewing angle of liquid crystal displays, and moreover brightness enhancement films for improving contrast of displays etc. are used.
Optical films such as the polarizing plate are cut into a predetermined size adapted to image viewing displays such as liquid crystal displays, and are supplied as an article of manufacture.
As the polarizer, a film made of polyvinyl alcohol as a main material is impregnated with dichroism materials such as iodine or dyes, and subsequently stretched to be used. Moreover, as a material of a protective film, triacetyl celluloses, polyethylene terephthalates, and acrylics based resins, polycarbonates, norbornene-based resins, etc. are used. However, polyvinyl alcohol that is a main material of the polarizer is a material having high hydrophilic property, and is swelled and dissolved during long time water immersion. Although protective films protect both side surfaces of a polarizer, a cut end face (cut plane) of the cut optical film exposes the bare polarizer.
Therefore, when an optical member including hydrophilic materials, such as a polarizer, is left standing under an atmosphere with high temperature and high humidity for a long time, or when water contacts the end face of the optical member caused by dew condensation etc., swelling, dissolution, etc. of the polarizer (especially hydrophilic materials, such as polyvinyl alcohol) is occurred, and in consequence, an original shape of the optical member cannot be maintained. Which, as a result, may occasionally raise defects such as increased transmittance as an optical member, decolorization etc.
As technique for improving properties of cut end faces of optical members, a technique for solving defect concerning an adhesive layer of an adhesive type optical member having an adhesive layer(s) provided therein is proposed. For example, Japanese Patent Laid-Open No. 11-129355, Japanese Patent Laid-Open No. 11-254550, and Japanese Patent Laid-Open No. 2000-258628. Japanese Patent Laid-Open No. 11-129355 discloses a technique for forming layer with thermoplastic resin powders to an edge side of an adhesive layer, and Japanese Patent Laid-Open No. 11-254550 discloses a coating technique for an end face of an optical member with non-adhesive layer. Moreover, Japanese Patent Laid-Open No. 2000-258628 discloses a technique of attaching powders to an edge side of an adhesive layer. Such techniques aim at preventing defects resulting from pollution by protrusion and deposition of the adhesives by covering the adhesive layer exposed open in the end face.
Moreover, a liquid crystal display is disclosed in which a periphery of a polarizing plate attached on a transparent substrate of a liquid crystal cell is covered with sealants (Japanese Patent Laid-Open No. 8-320485). However, in a liquid crystal display panel where a narrower edge and an expanded display area are increasingly required, application of the liquid crystal display described in Japanese Patent Laid-Open No. 8-320485 increases possibility of exposure of section covered by the sealant. Which as a result, disables prevention of defects of the optical member by exposing a section of sealing member.